sed command 's use

sed ‘3q’ /etc/passwd
Meanning :-
Quits after reading 3 lines.

$ sed ‘1,3p’ /etc/passwd

Sed by default prints all lines it processed on standard output. A p command will cause line 1 to 3 be printed twice

$ sed –n ‘1,3p’ /etc/paswd

It suppresses duplicate lines. Remember to user –n whenever using p command.

$ sed –n ‘9,11p’ /etc/passwd


Selects lines numbers 9 through 11.

The s (substitute) helps us in replacing a pattern in the file with something else. The syntax is -

s///

$ sed ‘1,5s/director/member /’emp.lst

The instruction replaces the left-most occurrence of the string director in the current line with the string member

$ sed ‘s/:/ /g’ /etc/passwd

Replaces all occurrences of : with a space with the g flag.